1. Field of the Invention
The present invention relates to an image forming device and an image forming method. More particularly, the present invention relates to an image forming device and an image forming method including a toner cartridge arranged to supply toner to a developing unit all at one time.
2. Description of Related Art
An electrophotographic image forming device has a photosensitive body, exposing unit, developing unit, transfer unit and fusing unit as main components. When the developing unit supplies toner to a photosensitive drum, the toner is attached to an electrostatic latent image formed on a surface of a photosensitive drum by an exposing unit, and as a result, the electrostatic latent image is developed as a toner visible image. Thereafter, the transfer unit transfers the toner visible image onto paper, and, further, the fusing unit fuses the toner visible image on paper by heating and applying pressure.
The remaining toner in the developing unit is important information for maintenance and management. Hence, there is known an image forming device that is provided with a toner concentration sensor in the developing unit to detect a toner concentration in the developing unit. The toner concentration sensor detects that toner in the developing unit becomes empty when an output continuously goes below a threshold a predetermined number of times. In this image forming device, toner is replenished from a toner bottle to the developing unit during each toner replenishing operation. In contrast, there is also known an image forming device of a type of replenishing the total amount of toner in a toner unit to the developing unit at one time.
In the latter image forming device, toner is replenished in a state where some toner still remains in the developing unit. This is because a roller and other components are likely to deteriorate when the developing unit is driven in a state where the toner has completely run out.